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Inhibition of presynaptic activity by zinc released from mossy fiber terminals during tetanic stimulation
Author(s) -
Minami Akira,
Sakurada Naomi,
Fuke Sayuri,
Kikuchi Kazuya,
Nagano Tetsuo,
Oku Naoto,
Takeda Atsushi
Publication year - 2006
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.20714
Subject(s) - mossy fiber (hippocampus) , tetanic stimulation , chemistry , stimulation , extracellular , hippocampal formation , biophysics , long term potentiation , neuroscience , granule cell , calcium , biochemistry , dentate gyrus , biology , receptor , organic chemistry
Zinc exists in high densities in the giant boutons of hippocampal mossy fibers. On the basis of the evidence that zinc decreases extracellular glutamate concentration in the hippocampus, the presynaptic action of zinc released from mossy fibers during high‐frequency (tetanic) stimulation was examined using hippocampal slices. The increase in zinc‐specific fluorescent signals was observed in both extracellular and intracellular compartments in the mossy fiber terminals during the delivery of tetanic stimuli (100 Hz, 1 sec) to the dentate granule cell layer, suggesting that zinc released from mossy fibers is immediately retaken up by mossy fibers. When mossy fiber terminals were preferentially double‐stained with zinc and calcium indicators and tetanic stimuli (100 Hz, 1 sec) were delivered to the dentate granule cell layer, the increase in calcium orange signal during the stimulation was enhanced in mossy fiber terminals by addition of CaEDTA, a membrane‐impermeable zinc chelator, and was suppressed by addition of zinc. The decrease in FM4‐64 signal (vesicular exocytosis) during tetanic stimulation (10 Hz, 180 sec), which induced mossy fiber long‐term potentiation, was also enhanced in mossy fiber terminals by addition of CaEDTA and was suppressed by addition of zinc. The present study demonstrates that zinc released from mossy fibers may be a negative‐feedback factor against presynaptic activity during tetanic stimulation. © 2005 Wiley‐Liss, Inc.